1. Field of the Invention
The invention relates to outlet gate arrangements for hoppers and particularly to those of pneumatic discharge systems utilized on railway hopper cars.
2. The Prior Art
The prior art discloses pneumatic discharge systems for hoppers having a tubular element at the bottom thereof open at the top for communication with the hoppers and arranged for connection at its opposite ends to a pneumatic conveyor system and the closures have consisted of tubes rotatably mounted within the tubular element and formed with elongated or helical slots registrable with the discharge opening from the hopper into the tubular outlet. Examples of the tubular closure type of pneumatic hopper outlet appear in McCausland et al U.S. Pat. No. 3,067,774, Koranda U.S. Pat. No. 3,583,768 and Mundinger et al U.S. Pat. No. 3,675,975. The prior art also discloses pneumatic hopper outlets utilizing gate members slidable transversely of the hopper discharge opening, as exemplified in Adler U.S. Pat. No. 3,637,262, Schuller U.S. Pat. No. 3,693,846 and Shaver et al U.S. Pat. Nos. 3,693,839 and 3,700,143.